When a person or object approaches high speed door, it is automatically detected by sensors or it generates a start signal when a button is operated at random, and forwards it to the controller.
When the start-up signal occurs, the processing department starts the engine to open the speed door, and the position of the door is monitored by the location detection department to slow down and fully open it.
If no signal is given to the sensor after a period of time, the controller will start closing door by reversing the engine and reading the door position from the position detector to the end. and it slow it down just before it is fully closed.
In normal high speed doors, location of doors is detected by a large number of proximity switches and many types of limit switches are used in large industrial speed door, but the automatic doors with micom(Details after) are very precise encoders that can detect engine rotational and speed.
1.1. Infrared detectors
There are two types: passive and active.
Infrared are released from the human body. Radiative energy is released when temperatures above absolute zero ̊k (Sub -273 ̊c) are present in all animals, plants or even inanimate objects, as well as in humans. Infrared is radiated from relatively low temperatures, such as humans. This type of device that directly detects infrared radiation from an object is called passive type.
Infrared switches are also used in homes.
There are remote controls such as televisions and sound devices. These buttons allow remote control of various controls such as on/off of the power supply as well as channel or volume control. However, unlike the passive type sensors described in the previous description, they need a separate device that emits infrared light and a device that receives infrared light. like this separate receiver is called an active type.
about the infrared rays
Infrared is a type of radio, television, etc. radio waves, or electromagnetic waves such as regular visible light (light) or x-rays, which are fairly wide wavelengths that cannot be seen in human eyes with longer wavelengths. Infrared rays also have very similar properties to light.
1.1.1 Passive Type Detector
As mentioned earlier, infrared radiation is emitted from the human body, and sensors that directly detect infrared light are called passive sensors, and they are also referred to as ultra-conductive detectors.
At the human body temperature of 36°C, a large amount of infrared radiation of 6.5 μm to 15 μm centered around 10 μm is emitted.
Many types of sensors that detect this are commercialized, and are used in a variety of applications, including automatic door detectors, protective devices, and safety applications.
1.1.2 Active Detector
A detector ignores infrared radiation emitted from a subject (sensor water) and attaches an infrared radiation device to the detector itself, then scans it towards it and detects it reflecting back.
Active type uses infrared radiation ranging from 1 μm to 3μm, and its properties are especially similar to general light (visual ray), so it has been used for various optical systems.
Active types are again divided into reflective and floodlighting-blocking, showing the below.
1.2 Radar Sensor
Radar reminds me of military aircraft surveillance and airport control facilities.
Radar sensors are made of the same principle, which is a detector that uses the Doppler effect and is sometimes referred to as a Doppler sensor.
Radar sensors can be detected for a relatively long distance compared to infrared types and are advantageous for large automatic doors, but there are disadvantages of detecting unwanted objects in automatic doors such as snow and rain, which can cause malfunction of automatic doors.
What is the Doppler Effect?
Objects moving within the detection range produce an intermediate frequency signal depending on the direction and speed of the movement.
If you listen to the horn without moving as the train goes by with a long horn you may have experienced a sudden drop in the tone when the train comes up and goes over.
This phenomenon is called the Doppler effect, and frequency increases when objects are close, while frequency decreases when they are distant.
As the frequency difference increases as the speed of the moving body increases , the application enables the measurement and detection of various moving objects such as speed gun, which can measure the speed of a thrown baseball or a moving car.
1.3 Other detectors
there are various other detector such as A loop coil detector that detects various vehicles such as a forklift, an electric mat switch that uses a person’s weight, a magnetic card reader that can only open and close, and a number key that can be pressed lightly by a person.
Recently, there is a system that recognizes people’s faces using computers to open and close automatic doors, and fingerprint readers, iris recognizer, and voice recognition devices are sometimes used for automatic doors.
2. Processing parts
Controller that controls high speed doors and logic control (Logic control) using electronic interface such as relay, magnetet switch, and electronic components such as IC
2.1 Sequence Control
Using contacts such as magnet switch and auxiliary relay, run the engine in the order specified by the sensor and limit switch to move the door. It was used a lot in early days, but due to the difficulties of precise control, it is now used in large industrial gates and rarely found in small automatic doors.
2.2 Logic Control
The basic principle is similar to the concept control, but it is made from a combination of IC and various electronic components, and is widely used in automatic doors as it can be applied to various controllers along with the development of electronic parts industry. because it can get precision and stability at relatively low prices.
2.3 Micom Controls
Recently, demands for smarter and more versatile products are increasing and becoming popular. With the low price of micro-processors, the use of single chip microcomputers is becoming common throughout the industry, and more precise and advanced rapid door are being developed with a variety of functions built into the factory speed doors with micro-computer.
It is simple and reduces possibility of failure because there is no need for limit switches or proximity switches that are necessary to check door positions that are attached to them.
What is the Micom?
Micom refers to a microcomputer and has two formats.
A device made from a single chip (CCP) and a memory I/O port is called the One Chip micro processor.
Generally, One board micro processor is used for small controllers and one board micro processor for computers such as personal computers.
3. Engine parts
Consists of the engine (motor), the moderator, and the power transfer unit (belt, chain, etc.).
The engine may think of AC motor, DC motor, and stepping motor, but most of AC motor or DC motor are used considering price and driving force.
Considering rotational force and control characteristics, DC motor is excellent, but only when operated momentarily, the rest of the time is left stationary.
Therefore, AC motors are also used to improve torque characteristics, taking into account the decrease in heating characteristics.
Frequent operation and shutdown require a extra motor power to operate smoothly, but if too strong, it may be dangerous to trap a person in the door, so proper force placement is required.
The moderator structure is possible but shall be able to open and close the door by hand at blackout or power-off.
4. Location detector parts
Because the automatic doors always operate within the specified area, both ends of the stop and brake positions shall be detected.
The micom type can usually be calculated by detecting the direction of rotation and the amount of rotation of the motor from an encoder coupled to the engine, but a limit switch that can detect the position of the door directly is required for the test or logic type.
4.1 Limit Switch
Micro switch and magnetic proximity switch are used.
4.1.1 Micro Switch
This is also commonly referred to as a limit switch and works when applying a physical (mechanical) force. It is installed at each end of the door and at the brake position, and when the door opens and closes, press the actuator to detect it.
4.1.2 Magnetic proximity limit switch
This device operates the Reed switch with the suction force of the magnet. Lead switches are filled with inert gas and are highly reliable for high sensitivity and high speed operation.
but its should be careful that metals near magnets and lid switches can cause malfunction.
A device that generates a signal that encodes the rotational state of a motor.
There is an Incremental type, which can detect rotational speed and direction only, and Absolute, which can read absolute positions for speed, direction and rotation angle, but the Incremental type, which is usually used in automatic doors.
The Incremental type encoder has an optical encoder with an optical system, and a magnet encoder with an magnetic system.
4.2.1 Magnet encoder
As shown in the figure, a circular magnet with a uniform spacing between the N and S poles rotates as the motor rotates, and the stimulation is detected with a Hale detector to measure the amount of rotation.
4.2.2 Optical encoder
when motor rotates, detector measure the amount of rotation by detecting the infrared beam passing through the slot of disc.
Both of the above methods are used for various controls and PVC door, and the more stimuli or slots are placed on the plate, the more precise they can be, but it is more difficult to produce and should be suitable for processing capability in micom.
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